As a comprehensive intelligent information system that integrates wireless technology, embedded technology, and sensor network technology, a sensor network may be applied in various fields such as public security, ecology and environment, emergency management, intelligent transport, anti-terrorism, intelligent home, etc. For example, a sensor/ controller network in intelligent home, collection of various parameters in an industrial site, and uniform networking regulation of controllers, etc., can be implemented through a sensor network.
In the existing ubiquitous sensor network (USN) scenario, the number of sensor nodes or sensor networks, as well as the number of sensor application users, is huge. With the increase of the number of sensor nodes or sensor networks and the number of sensor application users, a single access node in the Internet for accessing sensor networks into the Internet has a too heavy load, such that the sensor nodes or sensor networks and the sensor application users are affected by a delay caused by queuing at the access node, thereby increasing an end-to-end delay. Besides, a sensor node or sensor network will support more and more applications. Some of these sensor applications have a high QoS requirement. For example, QoS of a medical care system requires that packets should not be lost; therefore, it is suitable to run in a 3GPP access system; while other applications, for example, transfer of weather forecast data, they are insensitive to packet loss and therefore suitable for running in other complementary access systems, for example a WiFi access network.
The existing multi-homing and load balance solutions for mobile nodes comprises adopting a proxy mobile IPv6 (Proxy Mobile IPv6, PMIPv6) technology.
In the traditional PMIPv6 multi-homing technology, when a new mobile access gateway (MAG) is newly associated via a new interface, the new MAG sends a proxy binding update message to a local mobility anchor LMA to register a new care-of-address. In the proxy binding update message, the new MAG sets an access technology (for example, adopting a WiFi access technology or a 3G access technology, etc.) and a handoff indicator HI value. If the type of the access technology is different from the corresponding value of the node in current binding cache entry and the HI value is 2, the LMA determines that a handoff occurs between different access technologies. The LMA then sends as a response a proxy binding confirmation message to the MAG, in which confirmation message, HI is set as 2.
The following problems would arise if a traditional PMIPv6 multi-homing technology is used in a large scale ubiquitous sensor network:
In the traditional PMIPv6 multi-homing technology, the HI value must be set as 2. However, in real application, when a new interface is activated and accessed to a new MAG, the new MAG generally sets the HI value to 1 so as to indicate association to the new interface, instead of setting the HI value to 2.
In the traditional PMIPv6 multi-homing technology, the new MAG sets an HI value in a proxy binding update message that is sent to the LMA. It means that terminal node needs to notify the new MAG that the terminal node is a multi-homing node. However, in a USN environment, because a sensor node generally has a low energy and a poor processing capability, such sensor node will not tell the new MAG whether the present node is a multi-homing node. Thus, the new MAG should determine in other way whether the node is a multi-homing node.
Besides, it is easy for an MAG and an LMA which support a single access technology to correctly set the type of the access technology. However, in a USN environment, the sensor node or sensor network might access to the Internet through different access technologies. In other words, the MAG and the LMA may have different access technologies. In a scenario of multiple access technologies, it is hard to correctly set the access technology.